One of the key uncertainties surrounding the impacts of climate change in Africa is the effect on the sustainability of rural water supplies. Many of these water supplies abstract from shallow groundwater (<50 m) and are the sole source of safe drinking water for rural populations. Analysis of existing rainfall and recharge studies suggests that climate change is unlikely to lead to widespread catastrophic failure of improved rural groundwater supplies. These require only 10 mm of recharge annually per year to support a hand pump, which should still be achievable for much of the continent, although up to 90 million people may be affected in marginal groundwater recharge areas (200-500 mm annual rainfall). Lessons learnt from groundwater source behaviour during recent droughts, substantiated by groundwater modelling, indicate that increased demand on dispersed water points, as shallow unimproved sources progressively fail, poses a much greater risk of individual source failure than regional resource depletion. Low yielding sources in poor aquifers are most at risk. Predicted increased rainfall intensity may also increase the risk of contamination of very shallow groundwater. Looking to the future, an increase in major groundwater-based irrigation systems, as food prices rise and surface water becomes more unreliable, may threaten long-term sustainability as competition for groundwater increases. To help prepare for increased climate variability, it is essential to understand the balance between water availability, access to water, and use/demand. In practice, this means increasing access to secure domestic water, understanding and mapping renewable and non-renewable groundwater resources, promoting small-scale irrigation and widening the scope of early warning systems and mapping to include access to water.Key words groundwater; climate; Africa; water supply; drought; agriculture Quel impact aura le changement climatique sur les approvisionnements ruraux en eaux souterraines en Afrique? Résumé Une des incertitudes principales concernant les impacts du changement climatique en Afrique est l'effet sur la durabilité des approvisionnements ruraux en eau. Nombre de ces approvisionnements prélèvent dans des nappes souterraines peu épaisses (<50m) et sont l'unique source sûre d'eau potable pour les populations rurales. Les analyses des études existantes de précipitations et de recharge suggèrent que le changement climatique est peu susceptible de conduire à une défaillance catastrophique généralisée des ressources rurales améliorées en eaux souterraines. Ces dernières ne nécessitent que 10 mm de recharge par an pour satisfaire une pompe manuelle, ce qui devrait être réalisable pour une grande partie du continent, bien que 90 millions de personnes puissent être affectés dans des zones marginales de recharge en eaux souterraines (200-500 mm de pluviosité annuelle). Les leçons apprises sur les comportements des ressources souterraines au cours des sécheresses récentes, renforcées par des modélisations hydrogéologi...

14Groundwater is increasingly being used for public and private water supplies in Scotland, but 15 there is growing evidence that manganese (Mn)

Interest in dissolved methane (CH) concentrations in aquifers in England, Scotland and Wales ('Great Britain' or GB) has grown concurrently with interest in the exploitation of unconventional gas sources (UGS). Experience, mainly from North America, has shown the importance of a pre-production baseline against which changes possibly due to UGS extraction can be compared. The British Geological Survey, aided by water utilities, private users and regulators, has compiled a unique dataset for CH in groundwaters of GB. This focuses principally on areas where UGS exploration is considered more likely, as indicated by the underlying geology. All the main water supply aquifers (Principal aquifers) were targeted, plus Secondary aquifers where locally important. The average dissolved CH concentration across GB in the aquifers sampled was 45μg/l. Out of a total of 343 sites, 96% showed dissolved CH concentrations <100μg/l, 80% <10μg/l, and 43%<1μg/l. No site had a CH concentration above the US Department of the Interior suggested risk action level of 10,000μg/l. While most sites were sampled only once, a subset was monitored quarterly to determine the magnitude of seasonal or other variations. Generally these variations were minor, with 84% of sites showing variations within the range 0.5-37μg/l, but some aquifers where the porosity was primarily fracture-related showed larger changes (0.5-264μg/l). This may have been due to the nature of sampling at these sites which, unlike the others, did not have installed pumps. Since the regulatory compliance monitoring attending UGS operations will include the measurement of parameters such as dissolved CH, it is essential that sampling methods are tested to ensure that reliable and comparable datasets can be obtained.

ABSTRACT:Urban planners and developers in some parts of the United Kingdom can now access geodata in an easy-to-retrieve and understandable format. 3D attributed geological models and associated GIS outputs developed by the British Geological Survey (BGS) provide a predictive tool for planning site investigations for some of the UK's largest regeneration projects in the Thames and Clyde River catchments. Page 2 S.D.G.Campbell et al. 3D modelling and related datasets for Urban Development -A case study in Glasgow-Clyde, UK Using the 3D models, planners can get a 3D preview of properties of the subsurface using virtual cross-section and borehole tools in visualization software, allowing critical decisions to be made before any expensive site investigation takes place, and potentially saving time and money. 3D models can integrate artificial and superficial deposits and bedrock geology; and can be used for recognition of major resources (such as water, thermal and sand and gravel), for example in buried valleys; groundwater modelling; and assessing impacts of underground mining. A preliminary groundwater recharge and flow model for a pilot area in Glasgow has been developed using the 3D geological models as a framework. This paper focuses on the River Clyde and the Glasgow conurbation, and the BGS's Clyde Urban Super-Project (CUSP) in particular, which supports major regeneration projects in and around the City of Glasgow in the west of Scotland.

Abstract. Groundwater plays a significant role in glacial hydrology and can buffer changes to the timing and magnitude of meltwater flows. However, proglacial aquifer characteristics or groundwater dynamics in glacial catchments are rarely studied directly. We provide direct evidence of proglacial groundwater storage, and quantify multi-year groundwater-meltwater dynamics, through intensive and high resolution monitoring of the proglacial system of a rapidly retreating glacier, Virkisjökull, in SE Iceland. Proglacial unconsolidated glaciofluvial sediments comprise a highly permeable aquifer in which groundwater flow in the shallowest 20–40 m of the aquifer is equivalent to 4.5 % (2.6–5.8 %) of mean annual meltwater river flow, and 9.7 % (5.8–12.3 %) of winter flow. Groundwater flow through the entire aquifer thickness represents 9.8 % (3.6–21 %) of annual meltwater flow. Groundwater in the aquifer is actively recharged by local precipitation, both rainfall and snowmelt, and strongly influenced by individual precipitation events. Significant glacial meltwater influence on groundwater within the aquifer occurs in a 50–500 m river zone within which there are complex groundwater / meltwater exchanges. Stable isotopes, groundwater dynamics and temperature data demonstrate active recharge from river losses, especially in the summer melt season, with more than 25 % of groundwater in this part of the aquifer sourced from meltwater. Such proglacial aquifers are common globally, and future changes in glacier coverage and precipitation are likely to increase the significance of groundwater storage within them. The scale of proglacial groundwater flow and storage has important implications for measuring meltwater flux, for predicting future river flows, and for providing strategic water supplies in de-glaciating catchments.